1. Field of the Invention
The present invention relates generally to the field of parts washing apparatus and methods, and particularly to a parts washing apparatus having a centrifugal filter to separate foreign waste elements from a cleaning solvent or other cleaning liquid.
2. Background Art
Parts washers are widely used in industrial applications, and in particular, automotive service shops. The more familiar part washer can be found in almost any service station in the United States. It is comprised of a sink (a wash basin) with a spigot and a drain that sits upon a standard 45 gallon drum. The drum functions as a reservoir and is partially filled with a parts washing solvent. The solvent is pumped from the drum and through the spigot, where it flows over the dirty part or parts and into the sink's drain, from which it flows through the drain into the drum. In this manner, the solvent continuously flows over the dirty parts while the operator washes the parts in the sink.
A problem with these conventional parts washers is that the foreign material washed from the dirty parts flows into the drum along with the solvent. In many applications, the foreign material will be comprised of contaminants, metal shavings, dirt, sand, grit, and oil particulates, and these will be referred to generally as “foreign matter”. Since much of this debris will remain suspended in the solvent while the pump is running, the pump is continuously subjected to substances that will damage its internal seals. Another problem is that after the solvent becomes sufficiently contaminated, it must be disposed of as contaminated waste and be given special treatment. This can be very expensive.
Much of the background art in this area has addressed this particular problem by placing a filter upstream of the pump to strain foreign debris from the solvent before it reaches the pump. For instance, in U.S. Pat. No. 4,056,114 (Boutillete), the pump is surrounded by a filter element. U.S. Pat. No. 3,890,988 (Lee) teaches a pump mounted at the top of a truncated cone that rests at the bottom of a solvent tank. The cone is made from a screen that is intended to filter the solvent before it reaches the inlet of the pump.
Additionally, the four patents cross-referenced above, namely U.S. Pat. No. 5,594,071, U.S. Pat. No. 6,068,707, U.S. Pat. No. 6,306,221 B1, and U.S. Pat. No. 6,398,877 B1, all show a wash basin to contain the solvent, and this solvent flows through a drain toward the reservoir which contains the solvent. However, instead of directing the solvent directly into the reservoir, it flows into a centrifugal filter which separates the undesirable foreign matter, such as fragments, crud, etc. from the solvent. The solvent which passes through the filter is moved by gravity into the underlying reservoir. Periodically after a quantity of the waste material collects within the filter element, the filter element with the contained foreign matter is periodically removed and sent to a disposal location. There is at the bottom part of the reservoir a pump which recirculates solvent in the reservoir upwardly into the basin. The subject matter of these two prior art patents are discussed further in the text of the patent application.
The method disclosed in these four patents noted above substantially reduces the problems of having to dispose of the contaminated waste, since it is much easier to do so with only the replaceable filter element, instead of more frequently disposing of the entire batch of solvent. However, there is another matter which deserves attention and this is that the fumes resulting from the solvent can be considered as environmentally objectionable. Thus, there exists a need to consider the precautions or measures that could be taken to limit the fumes that are emanated from the solvent.
It is toward these problems that the embodiments of the present invention are directed.